S&TEngineer wrote:......another spanner in the works. All the TCB section SPTs went to Lostwithiel box which controlled the Lostwithiel-Largin-Liskeard (exclusive) section. Only the Up Home at Liskeard had a telephone to Liskeard box.

Nick Allsop wrote:Liskeard hasn't been able to switch-out since the abolition of Largin in 1991, Lostwithiel is the first place with AB on the GW main line these days...

Just because the line is track circuit block both ways does not prevent it closing out so is there another reason why it can't close? Normally only a box with dissimilar block working would not be able to close (without closing the line that is).

Good point. Is the box fully colour-light now? If it still has semaphores, that could be a complication.

But just to be clear, at the date of the photograph of the two switches, the box appeared to be AB in one direction and TCB in the other. I believe there is (or was) a directive that in such cases, mixed working was not approved of and AB should be used at all times - maybe that was the reason the switches weren't used?

John Hinson wrote:Whichever, with semaphores it would make switching out on TCB complicated.

John

On a busy piece of railway potentially yes but down there all you would need is all tracks clear from the Home overlap to section signal (wrong term but it will suffice) overlap to be clear on both lines at the same time so that all the running signal can be pulled.

I think there are two switches at Pontrilas, linked by a bar. I recall being told that on one occasion (in the late 1960s), shortly after the provision of the two switches, by mistake only one was operated so that either the block instrument circuits or the telephone circuits (but not both) were switched through; result chaos!